Land use change and Sahel precipitation

Land use and land cover (LULC) over Africa have had substantial change over the last sixty years. This study examines the effect of these changes on African monsoon system and Sahel precipitation using a set of regional model simulations with various land-surface and cumulus parameterization schemes. While the magnitudes of the response vary from scheme to scheme, almost all the simulations show a decline in Sahel precipitation due to the long term expansion of pasture and crop land at the expense of trees and shrubs. Assessment of the degree of realism of each simulated response using various observations of precipitation suggests that observed historical land cover change can cause 15% to 20% decline in mean summer precipitation over the Sahel. The mechanism for the drying and its impacts in comparison to those of SST variability and global warming are discussed.